Which prenatal abdominal wall defect involves all layers of the abdominal wall, is associated with markedly elevated AFP, and features free-floating bowel in the amniotic cavity to the right of the umbilical cord?

• A. Gastroschisis
• B. Omphalocele
• C. Sacrococcygeal teratoma
• D. Renal agenesis

Answer: (A)

Gastroschisis is a true, full-thickness abdominal wall defect that lies to the right of the umbilicus, exposing bowel to the amniotic fluid. Because the abdominal contents aren’t covered by a sac, the fetal intestines float freely in the amniotic cavity and AFP levels in both amniotic fluid and maternal serum become markedly elevated. This combination—open, all-layer defect with free-floating bowel on ultrasound and high AFP—distinguishes gastroschisis from other entities. Omphalocele, for example, involves herniated contents that are contained within a membrane at the umbilicus, not free-floating and not typically right of the cord. Sacrococcygeal teratoma is a mass at the coccyx, and renal agenesis is not an abdominal wall defect at all.